Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

347
FXUS63 KLOT 092340
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
640 PM CDT Thu Apr 9 2026

.KEY MESSAGES...

- Showers and thunderstorms with locally heavy rainfall tonight.
  Amounts may exceed an inch and a half in some areas,
  particularly across northwestern IL, where new rises on area
  rivers and creeks may result.

- Warmer, but more active weather pattern with periods of
  storms returns late in the weekend through early next week.

- A threat for severe thunderstorms exists Tuesday and Wednesday
  of next week.

&&

.DISCUSSION...
Issued at 209 PM CDT Thu Apr 9 2026

A west-to-east oriented surface boundary has stalled across the
southern CWA (south of I-80) this afternoon. A few isolated
to widely scattered showers and storms may develop in it`s
vicinity this afternoon. In fact, there has already been some
hints at this across western IL. However, limited low-level
moisture is expected to curtail the threat of a higher coverage of
storms through late this afternoon. Accordingly, we expect most
areas will remain dry and mild through the remainder of the day,
with temperatures remaining in the 60s to the low to mid 70s
(warmest south).

As we head into this evening, a strengthening southwesterly low-
level jet will promote increasing moisture advection and
convergence right into the low/mid-level baroclinic zone north of
the stationary front into IA/western IL. This, in addition to the
associated strengthening frontogenetic ageostrophic circulation
will support the increasing coverage of showers this evening,
particularly across northwestern parts of the area (from the west-
northwest Chicago suburbs westward across the Rockford metro
area). There will also be a threat for embedded non-severe
thunderstorms and locally heavy rainfall with this activity given
the strongly forced ascent and rapidly moistening profile
(Precipitable water values up around 1.1"). Given the high soil
moisture and high river levels from previous heavy rain in the
past week, this heavy rain (which could exceed 1.5" in some areas
of northwestern IL) may result in at least some localized hydro
issues. Accordingly, to highlight this potential, we have issued
an ESF (Hydro outlook) north of I-80.

The focus for these showers and storms will gradually sag south-
southeastward with the frontal zone overnight into early Friday
morning. Accordingly, a gradual end in the rain is expected from
north-northwest to south-southeast late tonight through Friday
morning. Thereafter, dry weather is anticipated for the remainder
of the day Friday as a seasonably strong surface high begins to
build in from the northwest. Northerly winds in advance of this
surface high will result in a cooler day across the area on
Friday. As is typical this time of year, onshore north-
northeasterly flow will result in the coolest conditions (in the
low to mid 40s) near the Lake Michigan shore. Conversely, areas
farther inland should warm into the low to mid 50s north, and
closer to 60 far south. However, if cloud cover ends up remaining
more substantial during the afternoon, conditions could end up a
couple of degrees cooler than those currently advertised.

Global models/ensembles remain in good agreement with the upper
level pattern becoming more amplified this weekend as a deep upper
trough and closed low develops over the West Coast and downstream
ridging builds across the eastern CONUS. Locally, the surface
high pressure over the area Friday night will progress eastward
towards New England on Saturday. As this occurs, surface winds
will turn southeasterly during the day. While temperatures will
moderate back into the 60s for areas inland from the northeastern
IL Lake Michigan shore, the persistent onshore wind component
into northeastern IL will keep temperatures there several degrees
cooler Saturday afternoon. Broad warm/moist advection, tapping
low-level moisture from the western Gulf, then ramps up Saturday
night into Sunday downstream of surface low pressure which lifts
from the Plains into the upper Midwest. Accordingly, there will be
some low chances (30-40%) for showers and storms Saturday night
into Sunday amidst milder conditions, though the better chances
for showers and storms look to come later Sunday into Sunday
evening.

Even warmer (70s/80s temps), more humid (dewpoints into the 60s)
and more active weather is expected for at least the first half
of next week. During this period, a series of mid-level short
wave disturbances riding the fast southwest flow downstream of the
western CONUS upper trough look to take aim on our region. Of
particular forecast interest as we head into this emerging pattern
early next week, is the threat for a couple of episodes of severe
weather in our near our general region. This is still several
days away, so questions remain on the finer scale details.
However, in spite of this, there is enough of a larger scale
signal to support the SPC highlighting much of our area in a
threat area for severe thunderstorms next Tuesday and Wednesday.
Stay tuned!

KJB

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 640 PM CDT Thu Apr 9 2026

Forecast concerns include...

Isolated thunderstorms tonight with periods of rain.
Ifr/lifr cigs/vis tonight/Friday morning.
Wind shift to north/northeast this evening.

Periods of rain will gradually increase in coverage and
intensity through the evening with brief periods of heavy rain
possible during the early overnight hours. The rain will end
from northwest to southeast during the predawn hours with a few
showers lingering after daybreak.

There was a lightning strike recently near DPA and there may be
an isolated thunderstorm this evening but expected coverage is
too for mention at this time. There is a little better chance
for thunder late this evening into the overnight hours,
especially across northwest IL where vicinity thunder mention
at RFD looks on track. Its possible some thunder mention may be
needed during this time period for the Chicago terminals, but
confidence remains low at this time.

Winds are expected to become northerly in the next 1-2 hours and
then shift to the north/northeast for ORD/MDW. Only medium
confidence for both timing and wind directions and trends will
need to be monitored. Though the overall pattern would suggest
northeasterly winds across much of the area by mid/late evening.
Its possible speeds will increase into the 12-15kt range
overnight and then winds will turn back more northerly after
daybreak Friday. Prevailing northerly winds may continue for
much of Friday until shifting back northeast with a lake breeze
later in the afternoon.

Some brief mvfr vis is possible with the rain this evening
along with mainly vfr cigs. Cigs will lower into mvfr across
northwest IL later this evening and then quickly lower through
low mvfr and eventually to ifr during the overnight hours.
Mainly mvfr vis is expected with the rain overnight but the
heavier rain may lower vis into the 1-2sm range. Some brief lifr
cigs are possible but confidence is low for how widespread
these may become. Cigs will lift into mvfr by mid morning Friday
and are expected to lift to low vfr Friday afternoon. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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